Data communication networks may include various computers, servers, nodes, routers, switches, bridges, hubs, proxies, and other network devices coupled to and configured to pass data to one another. These devices will be referred to herein as “network elements”. The various network elements on the communication network communicate with each other using predefined sets of rules, referred to herein as protocols.
Different protocols are used to govern different aspects of the communication, such as how signals should be formed for transmission between network elements, various aspects of what the protocol data units should look like, how protocol data units should be handled or routed through the network by the network elements, and how information associated with routing information should be exchanged between the network elements.
Ethernet is a well known networking protocol that has been defined by the Institute of Electrical and Electronics Engineers (IEEE) as standards 802.1 and 802.3. Conventionally, Ethernet has been used to implement networks in enterprises such as businesses and campuses, and other technologies have been used to transport network traffic over longer distances. As the Ethernet standards have evolved over time, Ethernet has become more viable as a long distance transport technology as well.
A domain implemented using this Ethernet standard will be referred to as a Provider Bridging Network (PBN) or Backbone Bridging Network (PBBN) domain. 802.1Q, 802.1 ad, and 802.1 ah all use one or more spanning tree instances in the control plane to determine which links should be active and which should be blocked to prevent the formation of loops. An Ethernet network domain that implements one or more spanning trees on the control plane will be referred to herein as a spanning tree controlled Ethernet network domain.
Since a spanning tree requires all data to flow on particular selected links on the network, the network links that are part of the spanning tree may experience congestion. IEEE 802.1Qay was developed to allow traffic engineered paths to be defined on the network so that traffic could be forwarded over links not forming part of the spanning tree.
IEEE 802.1Qay defines Traffic Engineered Service Instance (TESI) which carries client layer or customer traffic under no failure or normal condition is called work or primary TESI. Upon failure of primary TESI, another backup TESI could be made to carry client layer or customer traffic; such TESI is called protect or backup TESI. Multiple backup TESIs could be associated with one primary TESI. Together, primary and backup TESIs form a group called Protection Group (PG). TESI PG is an end-to-end protection mechanism where each TESI is configured to traverse Backbone Edge Bridges (IB-BEBs) and Backbone Core Bridges (BCBs) by appropriately populating forwarding entries in the forwarding database (FDB).
The sequence of bridges (i.e., the physical resources or networking infrastructure) over which FDB is provisioned define an infrastructure segment. In general, a sequence of Local Area Network (LAN) ports and the intervening LANs and bridges form an infrastructure segment. End ports of an infrastructure segment are called Segment End-point Ports (SEPs). FIG. 1 shows an example when TESI is provisioned or routed through backup infrastructure segment under fault condition in a network.
Whenever the communication failure occurred on at least two tandem primary work infrastructure segments the TESI will be locally re-routed over backup or protection infrastructure segment of TESI. FIGS. 2 and 3 shows a topology, where we have two segment protection domains adjacent to each other. Unlike the topology shown in FIG. 2, we have forwarding ambiguity on bridge 6 (as shown in FIG. 3), because TESI forwarding entry is maintained on two ports of bridge 6 i.e. one towards node 4, and another towards node 5.
When segment between bridges 3 and 4 fails, TESI will be locally re-routed over backup infrastructure segment; thereby flowing over bridges 3-6-4. Bridge 6 has to forward the TESI data and control frames towards bridge 4. Since, TESI forwarding information is pre-provisioned on two ports of bridge 6: One towards bridge 4, and another towards bridge 5, over which port should bridge 6 forward the TESI? Thus there exist problem of forwarding ambiguity at bridge 6. Also, at bridge 6, the TESI has to retrace the path between bridge node B6 and B4 twice (i.e. TESI has to flow from B3-B6-B4 then return path B4-B6-B5) which leads to wastage of bandwidth and time in the network
For the reasons stated above, which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for protection of TESI over Adjacent Segment Protection Domain without Forwarding Ambiguity using Segment Protection Groups.